The wireless communication system mainly consists of a wireless access network and a core network, where the wireless access network is responsible for providing wireless connection so that the terminal connects to the core network level-by-level; while the core network (also called backbone network) connects the service provider with the access network, as well as the access network with other access networks, and performs unified management on service continuation, billing and mobility, and so on, of the terminal. For example, the Long Term Evolution (LTE) system consists of an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) and an Evolved Packet Core (EPC), as shown in FIG. 1. In the conventional LTE system, nodes in the access network (i.e. the evolved Node B (eNodeB, eNB)) are performed unified layout and deployment by the operator. The eNB, according to the network deployment, directly connects with the core network element such as the Mobility Management Entity (MME) and set up an S1 interface. The eNB can connect with a plurality of MMEs and select a suitable MME for the terminal in the process of the terminal access or handover.
However, with the continuous evolution of the wireless technology, more and more technical scenarios require that the access network nodes are dynamically deployed, and the nodes are even deployed by the users themselves in some scenarios. In order to control the dynamically deployed access nodes, the dynamic access node is often connected to the core network via the upper level static access node to form a hierarchical architecture of the access network. For example, the access network system with the hierarchical architecture can be a home base station system and a relay system technology.
The home base station is one kind of small and low-power base station deployed in indoor places such as the home and the office, and so on, and the main functions of the home base station is to provide the user with higher service rate, reduce high-speed service costs, and to make up for the deficiencies of the existing distributed cellular wireless communication system coverage. Benefits of the home base station comprise: boon, convenience, low-power output, and plug and play.
The users of the home base station access to the core network via the Home eNodeB Access Network (HeNB AN) (as shown in FIG. 2), where the HeNB AN consists of the Home eNodeB (HeNB) and the Home eNodeB Gateway (HeNB GW). The main functions performed by the HeNB GW comprise: dealing with home base station registration and access control, verifying the home base station, and being responsible for exchanging data of the core network and the home base station. Moreover, a Home eNodeB Management System (HeMS) performs operation and maintenance management on the home base station, and configures and controls the home base station according to the operator requirements, and primarily achieves a configuration management function for the HeNB. The configuration management function comprises location information verification, as well as parameter configuration for the HeNB. The parameter configuration is mainly related to the parameter configuration at the Core Network (CN) level, the parameter configuration on the Radio Access Network (RAN) side and the parameter configuration of Radio Frequency (RF). In addition, the HeNB also can adopt architecture of directly connecting to the MME without the HeNB GW.
RELAY or Relay Node (RN) is a radio network node which is used to solve problems of coverage and capacity of the cellular wireless communication system. In the cellular wireless communication system, the wireless coverage of the fixed base station network is limited due to various reasons, for example, reasons, such as a variety of building structures blocking the wireless signal and so on, cause that coverage holes exist inevitably in the wireless network coverage. On the other hand, at the edge area of the cell, due to the weakening of the wireless signal strength and interference of adjacent cells, the quality of communication is poor and the wireless transmission error rate increases when the UE is at the cell edge. The RN deployment can increase the data rate coverage, group mobility, temporary network deployment, throughput at the edge area of the cell and the coverage of new area. The RN relays data via the wireless link between the RN and other network nodes, and the working principle of the RN is shown as FIG. 3. In FIG. 3, the UE served directly by the base station is called a Macro UE, the UE served by the RELAY is called a RELAY UE. The RELAY UE accesses to the RELAY via the access link, and the latter relays data of the RELAY UE on the uplink and downlink via a backhaul link. Currently, the RELAY discussed in the 3rd Generation Partnership Project (3GPP) standards organization has all functions of the Macro eNB, and can set up the cell independently. The Macro eNB that provides the RELAY with the backhaul link is called Donor eNB (DeNB) of the RN, the interface between the RELAY and the DeNB is called a Un interface. From the signaling connection, a S1 connection is established between the RELAY and the DeNB, the DeNB acts as a S1 proxy of the RELAY, and the DeNB provides the control plane and user plane signaling connection (S1-C, S1-U) between the core network and itself via the S1 connection between the core network and itself. The RELAY attaches as a UE in the initialization process and acquires the Packet Data Network Connection (PDN), and on the connection, the RELAY sets up a service layer connection with its own Operation Administration and Maintenance (OAM) system, and downloads the configuration parameters.
From the above technical description of the home base station and the relay node, it can be seen that, the HeNB can access to the core network via the HeNB GW, and the RELAY accesses to the core network via the DeNB. In the hierarchical architecture, the signaling connection (i.e. S1 connection) that usually exists between the access network and the core network exists between the final access nodes (HeNB or RELAY) and the upper level access nodes (HeNB GW or DeNB); wherein, the final access node only has one S1 connection with the upper level access node, while the upper level access node might connect to different MMEs via a plurality of S1 connections. When the user terminal accesses to the final access node, the upper level access node chooses the appropriate MME for the terminal. However, the final access node cannot acquire the information of the MME to which the terminal accesses.